Aircraft Potable Water Use—Adequate hydration is particularly important for comfortable air travel. Aircraft typically are crowded with thousands of passengers including babies, small children, handicapped and others passing through a commercial passenger aircraft during a single week. Both passengers and crews contribute to microorganism populations aboard aircraft and special precautions must be taken to minimize and avoid the possibility of bacteria and other microorganisms being transferred to others through the water distribution system. A primary sanitation defense mechanism is to maintain an adequate residual of chlorine, preferably free chlorine, within the water storage and distribution system. However, water is supplied to aircraft from many locations and varies widely in taste and sanitary quality. Furthermore, leading causes of water borne disease, worldwide, are relatively large but still invisibly small, parasitic cysts such as Giradia and Crypto which are not controlled by chlorination. These pathogens can reliably be removed by effective microfiltration.
Aircraft Water Distribution and Management—Typically, a water distribution system on aircraft comprises a water storage tank and a centralized distribution line with various branches or legs extending from the central distribution line to locations throughout the aircraft. Water is distributed from the storage tank throughout the aircraft to galleys, lavatories and other locations as needed for food and beverage preparation, and for personal hygiene during flights. Galleys include coffee makers, water boilers and other drinking water service points. Similarly, lavatories often include drinking water outlets and may be used for face and hand rinsing, cleaning teeth and short term medication.
Water filter/purifier units, each comprising a housing pressure vessel (usually stainless steel) and a filtration/purification cartridge, are installed in or near galleys and lavatories as part of the aircraft water distribution system to improve water quality for consumption and for food and beverage preparation. Space in galley and lavatory compartments is expensive and severely limited. Accordingly, water filter/purifier units usually are installed in “out of the way” locations often behind other more readily accessible equipment and bulkheads.
Sanitation Practices—To overcome the challenges of virus, bacteria, and larger organism transmission via water systems and colonization within the aircraft potable water distribution systems, airlines, in addition to trying to assure an adequate chlorine residual within the aircraft water supply, periodically sanitize their aircraft water distribution systems with a 2+ hours soak of high concentration (100 ppm) chlorine solutions. The sanitation process is time and labor intensive and, because such high concentrations of chlorine is detrimental to the filtration/purification cartridges, requires removing the filtration/purification cartridges from the water filter/purifier units installed in galleys, fountains and lavatories throughout the aircraft prior to the sanitation process. After removal of cartridges, the housings (pressure vessels) must be reassembled to seal against leakage during sanitation. After chlorine flushing and soaking, the housings (pressure vessels) once again must be accessed, opened and the same or new cartridges must be installed. The housings (pressure vessels) frequently are installed in hard to reach locations, resulting in expensive labor costs alone sometimes ranging upwards to hundreds of dollars per unit.
System Draining and Refilling—Water must be drained from aircraft during periods of non-use (such as overnight) in cold climates. Proposed EPA regulations require much more frequent draining and filling of water storage tanks in an effort to improve aircraft drinking water quality and safety. Draining and filling water systems requires “vacuum breaks” at equipment locations to allow water to be properly released and “vents” to allow air to escape in order to assure proper functioning of filters, purifiers, and other equipment. Although the very latest filter/purifier units include automatic vacuum breaks and venting, most aircraft units require manual actuation often resulting in inadequate water draining and filling.
Also, under the proposed EPA regulations, it is likely that accessing and actuating manual vents and vacuum breaks, sometimes previously ignored, may become a significantly higher maintenance cost item due to difficult access to the water filter/purifier units and aircraft “out of service” revenue costs.
Microorganism Growth—Even with periodic sanitization, bacteria may colonize various branches (legs) of water distribution systems. Bacteria multiply rapidly, sometimes doubling in number in approximately 16 minutes. Therefore, a small number of bacteria may quickly reach infectious concentrations in water intended to be consumed, especially downstream of improperly installed/serviced filters/purifiers employed to remove chlorine, foul tastes, and odors. Further, water filter/purifier units installed in semi-remote locations along the water distribution system often require longer than desired distribution lines to specific service points (e.g., locations where the water is discharged from the water distribution system). These distribution lines provide unnecessary opportunities for previously purified water to be recontaminated from inadvertent inoculation, short term bacteria multiplication or biofilm formation/shedding that may have taken place in such distribution lines downstream of the water filter/purifier units.